In 2009, a law passed in California that allows drivers to mount a GPS on the windshield with a few restrictions. Driver side lower corner or passenger side lower corner. Here's the DMV website look at (12): http://www.dmv.ca.gov/pubs/vctop/d12/vc26708.htm
"(12) A portable Global Positioning System (GPS), which may be mounted in a seven-inch square in the lower corner of the windshield farthest removed from the driver or in a five-inch square in the lower corner of the windshield nearest to the driver and outside of an airbag deployment zone, if the system is used only for door-to-door navigation while the motor vehicle is being operated." From http://www.dmv.ca.gov/pubs/vctop/d12/vc26708.htm, the California DMV website.